<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <title>Three.js - Game w/notes</title>
    <style>
    html {
      box-sizing: border-box;
    }
    *, *:before, *:after {
      box-sizing: inherit;
    }
    html, body {
        margin: 0;
        height: 100%;
        user-select: none;
    }
    img, canvas {
        /* prevent the save-image on long press on mobile */
        pointer-events: none;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    #ui {
      position: absolute;
      left: 0;
      top: 0;
      width: 100%;
      height: 100%;
      display: flex;
      justify-items: center;
      align-content: stretch;
    }
    #ui>div {
      display: flex;
      align-items: flex-end;
      flex: 1 1 auto;
    }
    .bright {
      filter: brightness(2);
    }
    #left {
      justify-content: flex-end;
    }
    #right {
      justify-content: flex-start;
    }
    #ui img {
      padding: 10px;
      width: 80px;
      height: 80px;
      display: block;
    }
    #loading {
      position: absolute;
      left: 0;
      top: 0;
      width: 100%;
      height: 100%;
      display: flex;
      align-items: center;
      justify-content: center;
      text-align: center;
      font-size: xx-large;
      font-family: sans-serif;
        }
    #loading>div>div {
      padding: 2px;
    }
    .progress {
      width: 50vw;
      border: 1px solid black;
    }
    #progressbar {
      width: 0%;
      transition: width ease-out .5s;
      height: 1em;
      background-color: #888;
      background-image: linear-gradient(
        -45deg,
        rgba(255, 255, 255, .5) 25%,
        transparent 25%,
        transparent 50%,
        rgba(255, 255, 255, .5) 50%,
        rgba(255, 255, 255, .5) 75%,
        transparent 75%,
        transparent
      );
      background-size: 50px 50px;
      animation: progressanim 2s linear infinite;
    }

    @keyframes progressanim {
      0% {
        background-position: 50px 50px;
      }
      100% {
        background-position: 0 0;
      }
    }

    #labels {
      position: absolute;  /* let us position ourself inside the container */
      left: 0;             /* make our position the top left of the container */
      top: 0;
      color: white;
      width: 100%;
      height: 100%;
      overflow: hidden;
      pointer-events: none;
    }
    #labels>div {
      position: absolute;  /* let us position them inside the container */
      left: 0;             /* make their default position the top left of the container */
      top: 0;
      font-size: large;
      font-family: monospace;
      user-select: none;   /* don't let the text get selected */
      text-shadow:         /* create a black outline */
        -1px -1px 0 #000,
         0   -1px 0 #000,
         1px -1px 0 #000,
         1px  0   0 #000,
         1px  1px 0 #000,
         0    1px 0 #000,
        -1px  1px 0 #000,
        -1px  0   0 #000;
    }
  </style>
  </head>
  <body>
    <canvas id="c" tabindex="1"></canvas>
    <div id="ui">
      <div id="left"><img src="resources/images/left.svg"></div>
      <div style="flex: 0 0 40px;"></div>
      <div id="right"><img src="resources/images/right.svg"></div>
    </div>
    <div id="loading">
      <div>
        <div>...loading...</div>
        <div class="progress"><div id="progressbar"></div></div>
      </div>
    </div>
    <div id="labels"></div>
  </body>
<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js",
    "three/addons/": "../../examples/jsm/"
  }
}
</script>

<script type="module">
import * as THREE from 'three';
import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
import * as SkeletonUtils from 'three/addons/utils/SkeletonUtils.js';
import { GUI } from 'three/addons/libs/lil-gui.module.min.js';

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );

	const fov = 45;
	const aspect = 2; // the canvas default
	const near = 0.1;
	const far = 1000;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.set( 0, 40, 80 );

	const controls = new OrbitControls( camera, canvas );
	controls.target.set( 0, 5, 0 );
	controls.update();

	const scene = new THREE.Scene();
	scene.background = new THREE.Color( 'white' );

	function addLight( ...pos ) {

		const color = 0xFFFFFF;
		const intensity = 2.5;
		const light = new THREE.DirectionalLight( color, intensity );
		light.position.set( ...pos );
		scene.add( light );
		scene.add( light.target );

	}

	addLight( 5, 5, 2 );
	addLight( - 5, 5, 5 );

	const manager = new THREE.LoadingManager();
	manager.onLoad = init;

	const progressbarElem = document.querySelector( '#progressbar' );
	manager.onProgress = ( url, itemsLoaded, itemsTotal ) => {

		progressbarElem.style.width = `${itemsLoaded / itemsTotal * 100 | 0}%`;

	};

	const models = {
		pig: { url: 'resources/models/animals/Pig.gltf' },
		cow: { url: 'resources/models/animals/Cow.gltf' },
		llama: { url: 'resources/models/animals/Llama.gltf' },
		pug: { url: 'resources/models/animals/Pug.gltf' },
		sheep: { url: 'resources/models/animals/Sheep.gltf' },
		zebra: { url: 'resources/models/animals/Zebra.gltf' },
		horse: { url: 'resources/models/animals/Horse.gltf' },
		knight: { url: 'resources/models/knight/KnightCharacter.gltf' },
	};
	{

		const gltfLoader = new GLTFLoader( manager );
		for ( const model of Object.values( models ) ) {

			gltfLoader.load( model.url, ( gltf ) => {

				model.gltf = gltf;

			} );

		}

	}

	function prepModelsAndAnimations() {

		const box = new THREE.Box3();
		const size = new THREE.Vector3();
		Object.values( models ).forEach( model => {

			box.setFromObject( model.gltf.scene );
			box.getSize( size );
			model.size = size.length();
			const animsByName = {};
			model.gltf.animations.forEach( ( clip ) => {

				animsByName[ clip.name ] = clip;
				// Should really fix this in .blend file
				if ( clip.name === 'Walk' ) {

					clip.duration /= 2;

				}

			} );
			model.animations = animsByName;

		} );

	}

	// Keeps the state of keys/buttons
	//
	// You can check
	//
	//   inputManager.keys.left.down
	//
	// to see if the left key is currently held down
	// and you can check
	//
	//   inputManager.keys.left.justPressed
	//
	// To see if the left key was pressed this frame
	//
	// Keys are 'left', 'right', 'a', 'b', 'up', 'down'
	class InputManager {

		constructor() {

			this.keys = {};
			const keyMap = new Map();

			const setKey = ( keyName, pressed ) => {

				const keyState = this.keys[ keyName ];
				keyState.justPressed = pressed && ! keyState.down;
				keyState.down = pressed;

			};

			const addKey = ( keyCode, name ) => {

				this.keys[ name ] = { down: false, justPressed: false };
				keyMap.set( keyCode, name );

			};

			const setKeyFromKeyCode = ( keyCode, pressed ) => {

				const keyName = keyMap.get( keyCode );
				if ( ! keyName ) {

					return;

				}

				setKey( keyName, pressed );

			};

			addKey( 37, 'left' );
			addKey( 39, 'right' );
			addKey( 38, 'up' );
			addKey( 40, 'down' );
			addKey( 90, 'a' );
			addKey( 88, 'b' );

			window.addEventListener( 'keydown', ( e ) => {

				setKeyFromKeyCode( e.keyCode, true );

			} );
			window.addEventListener( 'keyup', ( e ) => {

				setKeyFromKeyCode( e.keyCode, false );

			} );

			const sides = [
				{ elem: document.querySelector( '#left' ), key: 'left' },
				{ elem: document.querySelector( '#right' ), key: 'right' },
			];

			// note: not a good design?
			// The last direction the user presses should take
			// precedence. Example: User presses L, without letting go of
			// L user presses R. Input should now be R. User lets off R
			// Input should now be L.
			// With this code if user pressed both L and R result is nothing

			const clearKeys = () => {

				for ( const { key } of sides ) {

					setKey( key, false );

				}

			};

			const handleMouseMove = ( e ) => {

				e.preventDefault();
				// this is needed because we call preventDefault();
				// we also gave the canvas a tabindex so it can
				// become the focus
				canvas.focus();
				window.addEventListener( 'pointermove', handleMouseMove );
				window.addEventListener( 'pointerup', handleMouseUp );

				for ( const { elem, key } of sides ) {

					let pressed = false;
					const rect = elem.getBoundingClientRect();
					const x = e.clientX;
					const y = e.clientY;
					const inRect = x >= rect.left && x < rect.right &&
                         y >= rect.top && y < rect.bottom;
					if ( inRect ) {

						pressed = true;

					}

					setKey( key, pressed );

				}

			};

			function handleMouseUp() {

				clearKeys();
				window.removeEventListener( 'pointermove', handleMouseMove, { passive: false } );
				window.removeEventListener( 'pointerup', handleMouseUp );

			}

			const uiElem = document.querySelector( '#ui' );
			uiElem.addEventListener( 'pointerdown', handleMouseMove, { passive: false } );

			uiElem.addEventListener( 'touchstart', ( e ) => {

				// prevent scrolling
				e.preventDefault();

			}, { passive: false } );

		}
		update() {

			for ( const keyState of Object.values( this.keys ) ) {

				if ( keyState.justPressed ) {

					keyState.justPressed = false;

				}

			}

		}

	}

	// function* waitFrames(numFrames) {
	//   while (numFrames > 0) {
	//     --numFrames;
	//     yield;
	//   }
	// }

	function* waitSeconds( duration ) {

		while ( duration > 0 ) {

			duration -= globals.deltaTime;
			yield;

		}

	}

	class CoroutineRunner {

		constructor() {

			this.generatorStacks = [];
			this.addQueue = [];
			this.removeQueue = new Set();

		}
		isBusy() {

			return this.addQueue.length + this.generatorStacks.length > 0;

		}
		add( generator, delay = 0 ) {

			const genStack = [ generator ];
			if ( delay ) {

				genStack.push( waitSeconds( delay ) );

			}

			this.addQueue.push( genStack );

		}
		remove( generator ) {

			this.removeQueue.add( generator );

		}
		update() {

			this._addQueued();
			this._removeQueued();
			for ( const genStack of this.generatorStacks ) {

				const main = genStack[ 0 ];
				// Handle if one coroutine removes another
				if ( this.removeQueue.has( main ) ) {

					continue;

				}

				while ( genStack.length ) {

					const topGen = genStack[ genStack.length - 1 ];
					const { value, done } = topGen.next();
					if ( done ) {

						if ( genStack.length === 1 ) {

							this.removeQueue.add( topGen );
							break;

						}

						genStack.pop();

					} else if ( value ) {

						genStack.push( value );

					} else {

						break;

					}

				}

			}

			this._removeQueued();

		}
		_addQueued() {

			if ( this.addQueue.length ) {

				this.generatorStacks.splice( this.generatorStacks.length, 0, ...this.addQueue );
				this.addQueue = [];

			}

		}
		_removeQueued() {

			if ( this.removeQueue.size ) {

				this.generatorStacks = this.generatorStacks.filter( genStack => ! this.removeQueue.has( genStack[ 0 ] ) );
				this.removeQueue.clear();

			}

		}

	}

	function removeArrayElement( array, element ) {

		const ndx = array.indexOf( element );
		if ( ndx >= 0 ) {

			array.splice( ndx, 1 );

		}

	}

	class SafeArray {

		constructor() {

			this.array = [];
			this.addQueue = [];
			this.removeQueue = new Set();

		}
		get isEmpty() {

			return this.addQueue.length + this.array.length > 0;

		}
		add( element ) {

			this.addQueue.push( element );

		}
		remove( element ) {

			this.removeQueue.add( element );

		}
		forEach( fn ) {

			this._addQueued();
			this._removeQueued();
			for ( const element of this.array ) {

				if ( this.removeQueue.has( element ) ) {

					continue;

				}

				fn( element );

			}

			this._removeQueued();

		}
		_addQueued() {

			if ( this.addQueue.length ) {

				this.array.splice( this.array.length, 0, ...this.addQueue );
				this.addQueue = [];

			}

		}
		_removeQueued() {

			if ( this.removeQueue.size ) {

				this.array = this.array.filter( element => ! this.removeQueue.has( element ) );
				this.removeQueue.clear();

			}

		}

	}

	class GameObjectManager {

		constructor() {

			this.gameObjects = new SafeArray();

		}
		createGameObject( parent, name ) {

			const gameObject = new GameObject( parent, name );
			this.gameObjects.add( gameObject );
			return gameObject;

		}
		removeGameObject( gameObject ) {

			this.gameObjects.remove( gameObject );

		}
		update() {

			this.gameObjects.forEach( gameObject => gameObject.update() );

		}

	}

	const kForward = new THREE.Vector3( 0, 0, 1 );
	const globals = {
		camera,
		canvas,
		debug: false,
		time: 0,
		moveSpeed: 16,
		deltaTime: 0,
		player: null,
		congaLine: [],
	};
	const gameObjectManager = new GameObjectManager();
	const inputManager = new InputManager();

	class GameObject {

		constructor( parent, name ) {

			this.name = name;
			this.components = [];
			this.transform = new THREE.Object3D();
			this.transform.name = name;
			parent.add( this.transform );

		}
		addComponent( ComponentType, ...args ) {

			const component = new ComponentType( this, ...args );
			this.components.push( component );
			return component;

		}
		removeComponent( component ) {

			removeArrayElement( this.components, component );

		}
		getComponent( ComponentType ) {

			return this.components.find( c => c instanceof ComponentType );

		}
		update() {

			for ( const component of this.components ) {

				component.update();

			}

		}

	}

	// Base for all components
	class Component {

		constructor( gameObject ) {

			this.gameObject = gameObject;

		}
		update() {
		}

	}

	class CameraInfo extends Component {

		constructor( gameObject ) {

			super( gameObject );
			this.projScreenMatrix = new THREE.Matrix4();
			this.frustum = new THREE.Frustum();

		}
		update() {

			const { camera } = globals;
			this.projScreenMatrix.multiplyMatrices(
				camera.projectionMatrix,
				camera.matrixWorldInverse );
			this.frustum.setFromProjectionMatrix( this.projScreenMatrix );

		}

	}

	class SkinInstance extends Component {

		constructor( gameObject, model ) {

			super( gameObject );
			this.model = model;
			this.animRoot = SkeletonUtils.clone( this.model.gltf.scene );
			this.mixer = new THREE.AnimationMixer( this.animRoot );
			gameObject.transform.add( this.animRoot );
			this.actions = {};

		}
		setAnimation( animName ) {

			const clip = this.model.animations[ animName ];
			// turn off all current actions
			for ( const action of Object.values( this.actions ) ) {

				action.enabled = false;

			}

			// get or create existing action for clip
			const action = this.mixer.clipAction( clip );
			action.enabled = true;
			action.reset();
			action.play();
			this.actions[ animName ] = action;

		}
		update() {

			this.mixer.update( globals.deltaTime );

		}

	}

	class FiniteStateMachine {

		constructor( states, initialState ) {

			this.states = states;
			this.transition( initialState );

		}
		get state() {

			return this.currentState;

		}
		transition( state ) {

			const oldState = this.states[ this.currentState ];
			if ( oldState && oldState.exit ) {

				oldState.exit.call( this );

			}

			this.currentState = state;
			const newState = this.states[ state ];
			if ( newState.enter ) {

				newState.enter.call( this );

			}

		}
		update() {

			const state = this.states[ this.currentState ];
			if ( state.update ) {

				state.update.call( this );

			}

		}

	}

	const gui = new GUI();
	gui.add( globals, 'debug' ).onChange( showHideDebugInfo );
	gui.close();

	const labelContainerElem = document.querySelector( '#labels' );
	function showHideDebugInfo() {

		labelContainerElem.style.display = globals.debug ? '' : 'none';

	}

	showHideDebugInfo();

	class StateDisplayHelper extends Component {

		constructor( gameObject, size ) {

			super( gameObject );
			this.elem = document.createElement( 'div' );
			labelContainerElem.appendChild( this.elem );
			this.pos = new THREE.Vector3();

			this.helper = new THREE.PolarGridHelper( size / 2, 1, 1, 16 );
			gameObject.transform.add( this.helper );

		}
		setState( s ) {

			this.elem.textContent = s;

		}
		setColor( cssColor ) {

			this.elem.style.color = cssColor;
			this.helper.material.color.set( cssColor );

		}
		update() {

			this.helper.visible = globals.debug;
			if ( ! globals.debug ) {

				return;

			}

			const { pos } = this;
			const { transform } = this.gameObject;
			const { canvas } = globals;
			pos.copy( transform.position );

			// get the normalized screen coordinate of that position
			// x and y will be in the -1 to +1 range with x = -1 being
			// on the left and y = -1 being on the bottom
			pos.project( globals.camera );

			// convert the normalized position to CSS coordinates
			const x = ( pos.x * .5 + .5 ) * canvas.clientWidth;
			const y = ( pos.y * - .5 + .5 ) * canvas.clientHeight;

			// move the elem to that position
			this.elem.style.transform = `translate(-50%, -50%) translate(${x}px,${y}px)`;

		}

	}

	function rand( min, max ) {

		if ( max === undefined ) {

			max = min;
			min = 0;

		}

		return Math.random() * ( max - min ) + min;

	}

	function makeTextTexture( str ) {

		const ctx = document.createElement( 'canvas' ).getContext( '2d' );
		ctx.canvas.width = 64;
		ctx.canvas.height = 64;
		ctx.font = '60px sans-serif';
		ctx.textAlign = 'center';
		ctx.textBaseline = 'middle';
		ctx.fillStyle = '#FFF';
		ctx.fillText( str, ctx.canvas.width / 2, ctx.canvas.height / 2 );
		return new THREE.CanvasTexture( ctx.canvas );

	}

	const noteTexture = makeTextTexture( '♪' );

	class Note extends Component {

		constructor( gameObject ) {

			super( gameObject );
			const { transform } = gameObject;
			const noteMaterial = new THREE.SpriteMaterial( {
				color: new THREE.Color().setHSL( rand( 1 ), 1, 0.5 ),
				map: noteTexture,
				side: THREE.DoubleSide,
				transparent: true,
			} );
			const note = new THREE.Sprite( noteMaterial );
			note.scale.setScalar( 3 );
			transform.add( note );
			this.runner = new CoroutineRunner();
			const direction = new THREE.Vector3( rand( - 0.2, 0.2 ), 1, rand( - 0.2, 0.2 ) );

			function* moveAndRemove() {

				for ( let i = 0; i < 60; ++ i ) {

					transform.translateOnAxis( direction, globals.deltaTime * 10 );
					noteMaterial.opacity = 1 - ( i / 60 );
					yield;

				}

				transform.parent.remove( transform );
				gameObjectManager.removeGameObject( gameObject );

			}

			this.runner.add( moveAndRemove() );

		}
		update() {

			this.runner.update();

		}

	}

	class Player extends Component {

		constructor( gameObject ) {

			super( gameObject );
			const model = models.knight;
			globals.playerRadius = model.size / 2;
			this.text = gameObject.addComponent( StateDisplayHelper, model.size );
			this.skinInstance = gameObject.addComponent( SkinInstance, model );
			this.skinInstance.setAnimation( 'Run' );
			this.turnSpeed = globals.moveSpeed / 4;
			this.offscreenTimer = 0;
			this.maxTimeOffScreen = 3;
			this.runner = new CoroutineRunner();

			function* emitNotes() {

				for ( ;; ) {

					yield waitSeconds( rand( 0.5, 1 ) );
					const noteGO = gameObjectManager.createGameObject( scene, 'note' );
					noteGO.transform.position.copy( gameObject.transform.position );
					noteGO.transform.position.y += 5;
					noteGO.addComponent( Note );

				}

			}

			this.runner.add( emitNotes() );

		}
		update() {

			this.runner.update();
			const { deltaTime, moveSpeed, cameraInfo } = globals;
			const { transform } = this.gameObject;
			const delta = ( inputManager.keys.left.down ? 1 : 0 ) +
                    ( inputManager.keys.right.down ? - 1 : 0 );
			transform.rotation.y += this.turnSpeed * delta * deltaTime;
			transform.translateOnAxis( kForward, moveSpeed * deltaTime );

			const { frustum } = cameraInfo;
			if ( frustum.containsPoint( transform.position ) ) {

				this.offscreenTimer = 0;

			} else {

				this.offscreenTimer += deltaTime;
				if ( this.offscreenTimer >= this.maxTimeOffScreen ) {

					transform.position.set( 0, 0, 0 );

				}

			}

		}

	}

	// Returns true of obj1 and obj2 are close
	function isClose( obj1, obj1Radius, obj2, obj2Radius ) {

		const minDist = obj1Radius + obj2Radius;
		const dist = obj1.position.distanceTo( obj2.position );
		return dist < minDist;

	}

	// keeps v between -min and +min
	function minMagnitude( v, min ) {

		return Math.abs( v ) > min
			? min * Math.sign( v )
			: v;

	}

	const aimTowardAndGetDistance = function () {

		const delta = new THREE.Vector3();

		return function aimTowardAndGetDistance( source, targetPos, maxTurn ) {

			delta.subVectors( targetPos, source.position );
			// compute the direction we want to be facing
			const targetRot = Math.atan2( delta.x, delta.z ) + Math.PI * 1.5;
			// rotate in the shortest direction
			const deltaRot = ( targetRot - source.rotation.y + Math.PI * 1.5 ) % ( Math.PI * 2 ) - Math.PI;
			// make sure we don't turn faster than maxTurn
			const deltaRotation = minMagnitude( deltaRot, maxTurn );
			// keep rotation between 0 and Math.PI * 2
			source.rotation.y = THREE.MathUtils.euclideanModulo(
				source.rotation.y + deltaRotation, Math.PI * 2 );
			// return the distance to the target
			return delta.length();

		};

	}();

	class Animal extends Component {

		constructor( gameObject, model ) {

			super( gameObject );
			this.helper = gameObject.addComponent( StateDisplayHelper, model.size );
			const hitRadius = model.size / 2;
			const skinInstance = gameObject.addComponent( SkinInstance, model );
			skinInstance.mixer.timeScale = globals.moveSpeed / 4;
			const transform = gameObject.transform;
			const playerTransform = globals.player.gameObject.transform;
			const maxTurnSpeed = Math.PI * ( globals.moveSpeed / 4 );
			const targetHistory = [];
			let targetNdx = 0;

			function addHistory() {

				const targetGO = globals.congaLine[ targetNdx ];
				const newTargetPos = new THREE.Vector3();
				newTargetPos.copy( targetGO.transform.position );
				targetHistory.push( newTargetPos );

			}

			this.fsm = new FiniteStateMachine( {
				idle: {
					enter: () => {

						skinInstance.setAnimation( 'Idle' );

					},
					update: () => {

						// check if player is near
						if ( isClose( transform, hitRadius, playerTransform, globals.playerRadius ) ) {

							this.fsm.transition( 'waitForEnd' );

						}

					},
				},
				waitForEnd: {
					enter: () => {

						skinInstance.setAnimation( 'Jump' );

					},
					update: () => {

						// get the gameObject at the end of the conga line
						const lastGO = globals.congaLine[ globals.congaLine.length - 1 ];
						const deltaTurnSpeed = maxTurnSpeed * globals.deltaTime;
						const targetPos = lastGO.transform.position;
						aimTowardAndGetDistance( transform, targetPos, deltaTurnSpeed );
						// check if last thing in conga line is near
						if ( isClose( transform, hitRadius, lastGO.transform, globals.playerRadius ) ) {

							this.fsm.transition( 'goToLast' );

						}

					},
				},
				goToLast: {
					enter: () => {

						// remember who we're following
						targetNdx = globals.congaLine.length - 1;
						// add ourselves to the conga line
						globals.congaLine.push( gameObject );
						skinInstance.setAnimation( 'Walk' );

					},
					update: () => {

						addHistory();
						// walk to the oldest point in the history
						const targetPos = targetHistory[ 0 ];
						const maxVelocity = globals.moveSpeed * globals.deltaTime;
						const deltaTurnSpeed = maxTurnSpeed * globals.deltaTime;
						const distance = aimTowardAndGetDistance( transform, targetPos, deltaTurnSpeed );
						const velocity = distance;
						transform.translateOnAxis( kForward, Math.min( velocity, maxVelocity ) );
						if ( distance <= maxVelocity ) {

							this.fsm.transition( 'follow' );

						}

					},
				},
				follow: {
					update: () => {

						addHistory();
						// remove the oldest history and just put ourselves there.
						const targetPos = targetHistory.shift();
						transform.position.copy( targetPos );
						const deltaTurnSpeed = maxTurnSpeed * globals.deltaTime;
						aimTowardAndGetDistance( transform, targetHistory[ 0 ], deltaTurnSpeed );

					},
				},
			}, 'idle' );

		}
		update() {

			this.fsm.update();
			const dir = THREE.MathUtils.radToDeg( this.gameObject.transform.rotation.y );
			this.helper.setState( `${this.fsm.state}:${dir.toFixed( 0 )}` );

		}

	}

	function init() {

		// hide the loading bar
		const loadingElem = document.querySelector( '#loading' );
		loadingElem.style.display = 'none';

		prepModelsAndAnimations();

		{

			const gameObject = gameObjectManager.createGameObject( camera, 'camera' );
			globals.cameraInfo = gameObject.addComponent( CameraInfo );

		}

		{

			const gameObject = gameObjectManager.createGameObject( scene, 'player' );
			globals.player = gameObject.addComponent( Player );
			globals.congaLine = [ gameObject ];

		}

		const animalModelNames = [
			'pig',
			'cow',
			'llama',
			'pug',
			'sheep',
			'zebra',
			'horse',
		];
		const base = new THREE.Object3D();
		const offset = new THREE.Object3D();
		base.add( offset );

		// position animals in a spiral.
		const numAnimals = 28;
		const arc = 10;
		const b = 10 / ( 2 * Math.PI );
		let r = 10;
		let phi = r / b;
		for ( let i = 0; i < numAnimals; ++ i ) {

			const name = animalModelNames[ rand( animalModelNames.length ) | 0 ];
			const gameObject = gameObjectManager.createGameObject( scene, name );
			gameObject.addComponent( Animal, models[ name ] );
			base.rotation.y = phi;
			offset.position.x = r;
			offset.updateWorldMatrix( true, false );
			offset.getWorldPosition( gameObject.transform.position );
			phi += arc / r;
			r = b * phi;

		}

	}

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const width = canvas.clientWidth;
		const height = canvas.clientHeight;
		const needResize = canvas.width !== width || canvas.height !== height;
		if ( needResize ) {

			renderer.setSize( width, height, false );

		}

		return needResize;

	}

	let then = 0;
	function render( now ) {

		// convert to seconds
		globals.time = now * 0.001;
		// make sure delta time isn't too big.
		globals.deltaTime = Math.min( globals.time - then, 1 / 20 );
		then = globals.time;

		if ( resizeRendererToDisplaySize( renderer ) ) {

			const canvas = renderer.domElement;
			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		gameObjectManager.update();
		inputManager.update();

		renderer.render( scene, camera );

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();
</script>
</html>
